1. Field of the Invention
This invention relates to an unsealing structure for shrink film sealed packages within which a piece of merchandise is enclosed by a film and a tag seal is affixed to the outer surface of the film.
2. Description of Prior Art
Measures for unsealing a shrink film sealed package within which a piece of merchandise is enclosed by a shrink film has been disclosed in the Japanese Publication Gazette JITSU KOU HEI No. 1-34215 entitled "STRUCTURE FOR PREVENTING RELABELING OF A TAG LABEL AFFIXED TO PACKAGES". In the above publication, a tearing line is formed beforehand in a certain portion of the film, and a tag label such as a bar code is affixed thereto. If the tag label is stripped off, then the portion of the film near the tearing line will remain adhered to the tag label and the film of the package will be easily ripped beginning along the tearing line. The above unsealing structure is well known and often used in packages of instant cup noodles, where polyvinyl resins are chosen as the material to comprise shrink films for ease of ripping.
However, some polyvinyl resins produce poisonous substances when they are burned. For the sake of protecting the clean environment, it is preferable to use polyethylene films.
However, polyethylene film possesses very good extendibility, even in the case having the above unsealing structure, the portion of the film near the tearing line extends only when it is desired to rip the film of the package along the tearing line. Thus, it is difficult to rip the film of the package along the tearing line occasionally.
Especially, in the case of packing semiconductor wafers by utilizing films which are thicker than those with very small thickness and used in the package of instant cup noodles, it is quite difficult to rip the polyethylene film of the package along the tearing line.